1. Field of the Invention
The invention relates in general to an image processing circuit and an image processing method, and more particularly to an image processing circuit and an image processing method capable of executing motion compensation according to an alternating current (AC) sum of absolute difference (SAD) or a direct current (DC) sum of absolute difference (SAD).
2. Description of the Related Art
Referring to FIG. 1, a motion estimation and compensation device is shown. The motion estimate and motion compensation (MEMC) device 1 comprises a motion estimation engine 11 and a motion compensation circuit 12. The motion estimation engine 11 executes motion estimation according to a current image and a reference image, so that the motion compensation circuit compensates an image by way of interpolation according to the result of motion estimation.
The motion estimation engine 11 comprises a block matching unit 111. The block matching unit 111 divides the current image into a plurality of blocks of equal size. Each block has a corresponding search region in the reference image. The block matching unit 111 calculates a direct current (DC) sum of absolute difference (SAD) of a current block and a reference block so as to locate the block most similar to the current block in the search region.
Referring to FIG. 1, FIG. 2, FIG. 3 and FIG. 4. FIG. 2 shows a reference image. FIG. 3 shows a current image. FIG. 4 shows an image with interpolation. However, when the display image flashes, the block matching unit 111 will be unable to locate the block most similar to the current block according to the DC SAD. For example, the local region 21 of FIG. 2 and the local region 31 of FIG. 3 are such as a vehicle lamp. The local region 21 is full dark, and the local region 31 is full bright. Since the difference between the pixels in the local region 31 and the pixels in the local region 21 is too large, the block matching unit 111 cannot locate the block most similar to the current block according to the DC SAD. Consequently, the motion compensation circuit 12 will produce an image compensated with interpolation as illustrated in FIG. 4 due to incorrect matching of blocks. The local region 41 corresponds to the local region 31 and the local region 21. The local region 41 may be deformed if the matching of blocks is incorrect.